Block machines are known in the prior art in various embodiments. Substantially, in a synchronized process a stone mould should be provided, a concrete mixture should be filled into the moulding cavities of the stone mould, the concrete mixture should be packed with a tamper and/or a vibrator, and subsequently the thus produced final concrete products, the so-called moulded articles, should be demoulded.
Here, it has been proven successful to charge the block machines with bolster pallets and to lower stone moulds onto the bolster pallets. In general, the stone mould is formed as an upwards and downwards open mould.
The concrete mixture is then filled from at least one concrete hopper into at least one feedbox and let from there into the mould cavities of the stone mould. Subsequently, the bolster pallet is moved with a vibration unit and/or the tamper is lowered into the stone mould onto the fresh concrete. In this way, the concrete is packed in the stone mould. In the next step the tamper and the stone mould are lifted again and the bolster pallet with the moulded articles is taken out of the block machine.
In order to move the movable members such as the stone mould or the tamper such block machines nowadays have at least one lifting device such as a hydraulic cylinder. This often acts via at least one supporting member on the member to be lifted such as a stone mould or a tamper.
The supporting member can be configured as a traverse. Typically, it is guided via a linear guide on longitudinal guiding members, for example on shafts. For that, it has at least one guiding means interacting with the longitudinal guiding member, for example a slide bearing, a bushing, or the like.
It has shown in the past that especially the heavy movable members such as the stone mould or the tamper tend to tilt or jam in their guides. By such a tilting for example the wearing of the bearings is reduced which in turn leads to higher operating times of the machine.
In order to substantially avoid such problems the employment of specific lifting devices for the supporting members has proven successful. Said lifting devices often consist of a drive that moves a balancing swing arm fixed on the upper side of the machine bed such that the supporting member connected with the swing arm via a interconnecting bar is moved vertically along the longitudinal guides. For the most part in the prior art two lifting devices each per supporting member laterally arranged on the machine bed are used.
However, this solution known from the prior art requires a number of movable parts and respective bearings as well as two drives per supporting member what on the one hand significantly increases the production and first costs for the block machine and the associated maintenance and repair costs. On the other hand, the construction and design of such a machine is relatively expensive and it results in a high space required for the individual components.